Plastic ball grid array devices (PBGA) provide has a large number of advantages over other package types, e.g. pin grid arrays. In a typical PBGA package 10 (FIG. 2), a printed circuit board (PCB) made from such material as bismaleimide triazine (BT) resin or ceramic (Al.sub.2 O.sub.3) is used as a substrate 12. In such a package, a silicon integrated circuit (IC) die is attached on one side of substrate 12, with solder balls on the opposite side of substrate 12, and the silicon IC is encapsulated by a molding compound 14.
Electrical connection between the silicon IC die and the solder balls are achieved by wire bonding, or by means of a flip-chip connection, to conductors or traces on the "die side" surface of substrate 12, from such conductors to traces, and then through vias to the opposite side of substrate 12, at which other conductors or traces are provided to couple the solder balls.
At present, BGA technology is cost-effective for applications in which a large number of "I/Os" or "pins" per package are required. For example, popular BGA packages include 119, 169, 225, 256, 313, 352, 420 or 625 balls. Although semiconductor devices requiring a lower number of I/O pins are very common, it is expensive to provide BGA packages at such low number of I/O's. If BT is used as the material for substrate 12, for example, the BT material cost may account for 50% of the package.
Typically, BT or ceramic is provided in single-element form 16 (FIG. 1) with dimensions of, for example, 45 mm by 187.5 mm. A manufacturer of BGA packages attempts to lay out the packages to maximize area utilization of element 16. In element 16, the completed devices 10 are singulated (indicated by the dotted lines 17 on the element 16) to result in individual BGA devices 10 (FIG. 2). The remaining portions of element 16 are simply discarded. Such discarded portions may amount to 20 to 40% of the total area of element 16. Clearly, therefore, minimize such discarded portions of the element 16 would significantly reduce manufacturing cost, making the significant advantages of PBGA packages available to smaller packages.